1 files changed, 106 insertions, 0 deletions
diff --git a/internal/command/githttp/push.go b/internal/command/githttp/push.go
new file mode 100644
index 0000000..3377baf
--- /dev/null
+++ b/internal/command/githttp/push.go
@@ -0,0 +1,106 @@
+package githttp
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+
+	"gitlab.com/gitlab-org/gitlab-shell/v14/internal/command/readwriter"
+	"gitlab.com/gitlab-org/gitlab-shell/v14/internal/config"
+	"gitlab.com/gitlab-org/gitlab-shell/v14/internal/gitlabnet/accessverifier"
+	"gitlab.com/gitlab-org/gitlab-shell/v14/internal/gitlabnet/git"
+	"gitlab.com/gitlab-org/gitlab-shell/v14/internal/pktline"
+)
+
+const service = "git-receive-pack"
+
+var receivePackHttpPrefix = []byte("001f# service=git-receive-pack\n0000")
+
+type PushCommand struct {
+	Config     *config.Config
+	ReadWriter *readwriter.ReadWriter
+	Response   *accessverifier.Response
+}
+
+// See Uploading Data > HTTP(S) section at:
+// https://git-scm.com/book/en/v2/Git-Internals-Transfer-Protocols
+//
+// 1. Perform /info/refs?service=git-receive-pack request
+// 2. Remove the header to make it consumable by SSH protocol
+// 3. Send the result to the user via SSH (writeToStdout)
+// 4. Read the send-pack data provided by user via SSH (stdinReader)
+// 5. Perform /git-receive-pack request and send this data
+// 6. Return the output to the user
+func (c *PushCommand) Execute(ctx context.Context) error {
+	data := c.Response.Payload.Data
+	client, err := git.NewClient(c.Config, data.PrimaryRepo, data.RequestHeaders)
+	if err != nil {
+		return err
+	}
+
+	if err := c.requestInfoRefs(ctx, client); err != nil {
+		return err
+	}
+
+	return c.requestReceivePack(ctx, client)
+}
+
+func (c *PushCommand) requestInfoRefs(ctx context.Context, client *git.Client) error {
+	response, err := client.InfoRefs(ctx, service)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+
+	// Read the first bytes that contain 001f# service=git-receive-pack\n0000 string
+	// to convert HTTP(S) Git response to the one expected by SSH
+	p := make([]byte, len(receivePackHttpPrefix))
+	_, err = response.Body.Read(p)
+	if err != nil || !bytes.Equal(p, receivePackHttpPrefix) {
+		return fmt.Errorf("Unexpected git-receive-pack response")
+	}
+
+	_, err = io.Copy(c.ReadWriter.Out, response.Body)
+
+	return err
+}
+
+func (c *PushCommand) requestReceivePack(ctx context.Context, client *git.Client) error {
+	pipeReader, pipeWriter := io.Pipe()
+	go c.readFromStdin(pipeWriter)
+
+	response, err := client.ReceivePack(ctx, pipeReader)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+
+	_, err = io.Copy(c.ReadWriter.Out, response.Body)
+
+	return err
+}
+
+func (c *PushCommand) readFromStdin(pw *io.PipeWriter) {
+	var needsPackData bool
+
+	scanner := pktline.NewScanner(c.ReadWriter.In)
+	for scanner.Scan() {
+		line := scanner.Bytes()
+		pw.Write(line)
+
+		if pktline.IsFlush(line) {
+			break
+		}
+
+		if !needsPackData && !pktline.IsRefRemoval(line) {
+			needsPackData = true
+		}
+	}
+
+	if needsPackData {
+		io.Copy(pw, c.ReadWriter.In)
+	}
+
+	pw.Close()
+}